In the packaging of integrated circuit devices, including processors, memory devices, and other integrated circuits, the use of BGAs has become increasingly popular by permitting a high density of inter-connections. BGAs provide a relatively low package profile and have very short lead lengths which provide improved electrical characteristics. BGAs may be utilized in multiple chip devices. Usually, balls or bumps of a BGA (BGA balls) are soldered to an array of pads on a printed circuit board for permanent connection to leads extending to other circuitry. However, in many instances, particularly during prototype debugging or burn-in, BGA's may be removably placed in a socket for testing or operations.
BGA sockets have been available for several years. Ordinarily, these sockets include a printed circuit board having an array of electrically conductive pads on its surface. The pads match the arrangement of the BGA balls on the BGA to be inserted. The BGA is then placed in the socket and is vertically pressed against the array of pads by a force normal to the package itself. In order to guarantee electrical contact, the typically required pressure load applied to contacts is about 50 to 100 grams per contact. Therefore, when there are high BGA ball counts, the mechanism to apply a uniform force may be large and cumbersome. Slight variations in the size of the BGA balls can require particularly excessive force, sufficient to deform the BGA balls so as to force all of the BGA balls into contact with the underlying pads.